UILabel text not being updated

You may be facing an issue with threading as mentioned in the comments above. If you have a method that runs on the main thread and does some activity (such as search a database), updates that you make to the UI will not be committed until the run loop gets control. So, if you have a long, time consuming task going on on the main thread, run this code after setting the text of the label:

- (void)doSomethingTimeConsuming    ... consume some time ...    ... set text of label ...    [[NSRunLoop mainRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:0.5]];    ... continue long operation ...}

This should flush out any UI changes that you have made. Although this may be a sensible and functional hack, it doesn't beat the alternative. I highly suggest that you perform your app's time consuming tasks on a background thread, and update the UI through the main thread using performSelectorOnMainThread:withObject:waitUntilDone:. See Apple's page on iOS Thread Management.

In my case the function that was updating was called from a touch recognizer on a thread, but the place in the function where I'm changing the value of the label's text property I put it back on the main thread:

dispatch_async(dispatch_get_main_queue(), ^{    [self.someLabel setText:someString];});

I had a UILabel showing a level number that would not update to the new level number on a UIViewController. The only viable solution I could find that worked was to call setNeedsDisplay on the main thread of the view controller that owned the UILabel

-(void)changeLevelLabel:(int)theLevel {dispatch_async(dispatch_get_main_queue(), ^{    self.levelLabel.text = [NSString stringWithFormat:@"%d",theLevel];    [self.levelLabel setNeedsDisplay];});

}

See http://iosdevelopmentjournal.com/blog/2013/01/16/forcing-things-to-run-on-the-main-thread/ for a more detailed explanation